Telegraph apparatus



J 1933- R. w. GILBERT 1,928,967

' TELEGRAPH APPARATUS Filed Dec. 6. 1932 v INVENTOR Roan 1; WARD 0/; asnr BY Q 'DW 1 4- M ATTORNEYS Patented Oct. 3, 1933 PATENT, OFFICE TELEGRAPH APPARATUS Boswell Ward Gilbert, Neshanic, N. 1.

Application December 6, 1932.

8 Claims.

This invention relates to telegraph transmitters; more particularly to improvements in keying devices for code sending.

An object of the invention is to simplify and I minimize the number of keying operations required for transmission of a message thereby relieving strain and avoiding fatigue of the operator.

A further object is to provide a keying device which automatically controls all time intervals in code sending with the exception of the long space; a device which automatically makes dashes as well as dots and spaces each accurately within the letter.

The apparatus of the present invention embodies a relay capable of breaking heavy currents and high voltages eliminating thereby the necessity of auxiliary keying relays, while permitting extremely close and comfortable operating 50. adjustments of the key contacts proper.

The invention operates on the principle of alternate charge and discharge of a condenser through a resistance, the rate of charge and discharge being adjusted in correspondence with the time intervals of the dots and dashes to be transmitted. The condenser charge controls the negative bias on the control grid of a thermionic tube for actuating a relay contained in' the space path thereof in correspondence with the signals.

.A special side action key is associated with the relay circuit in such manner that a succession of dots will automatically be transmitted so long as the key is held to one side of its neutral position; similarly a succession of.dashes will be transmitted while the key is deflected to the opposite side of neutral. In the neutral'position the relay is stalled and no signals sent.

The single figure of the drawingshows diagrammatically the circuit employed in achieving the novel results of the present invention together with such mechanical details as are requisite to an explanation of the operation.

Referring to the drawing there is shown a vacuum tube V having an anode or plate P, a cathode K and a grid G. The space path of the tube is energized from a direct potential source 13 arranged inacircuit'traced from anode to cathode, which containsa neon or glow discharge tube N and the winding of a telegraph relay D, energization of which attracts armature E against the restorlnggtension of a spring S1. Armature E pivoted at l, terminates at its opposite extremity in a lug 2 arranged by virtue of the tension'in spring S1, to actuate a switch arm F, pivoted at 3, against the restoring tension of a Serial No. 645,887

spring Sr associated therewith. Switch arm F is provided with contacts 4 cooperating with contacts 5 for actuating the keyed circuit extending to the transmitter 0 extending to an antenna circuit AGn.

Arranged in parallel relation with the serially connected neon tube N and winding of relay D, is a circuit traced from point 6 of the connection extending to anode or plate P, through normally closed contacts of a switch I, through normally closed contact 8 and resilient switch-blade 9 of a specially constructed telegraph sending key H, through the conductive support 10 to a resilient switch-blade ll cooperating with contact 12, through an adjustable resistance R1, normally closed contacts 13 associated with armature E. and finally through a second adjustable resistance R2 to point 15 of the lead extending to cathode K.

Since armature E is directly connected to the grid G of the tube, the grid will be negatively biased relative to the cathode to the extent of the potential drop across resistance Ra'due to the flow of plate current therethrough over the circuit traced. If e0 is the total potential -drop between points 6 and 15, the portion of this voltage which is negatively applied to the grid of tube V is evidently given by the expression:

Resistances R1 and R: thus provide an adiustable potentiometer arrangement for negatively biasing the grid of tube V to a desired potential.

Relay D has the characteristic common to electromagnetic relays of requiring a much larger current for operation than that upon which it releases. In the operation of the system disclosed herein the negative bias on the grid of tube V is so-adjusted by means of resistances R1 and R: in the manner explained, that so long as the sending key H is in the normal position shown, the current flowing through the winding of relay D is just below that required for operation, so that the relay is stalled.

Connected directly between cathode and grid of tube V is a condenser C preferably adjustable in convenient steps. Obviously condenser C will assume a charge corresponding to such potentials as are applied between grid and cathode. Conversely the biasing potential applied to the grid will vary in correspondence with the condenser charge.- It is byvirtue of the charge and discharge of condenser C through resistances in the manner now to be explained, that automatic transmission of dots and dashes is effected so long as the telegraph key H is held operated.

Key H, pivoted at 14, which is of the side action type is provided with non-resilient arms 16 and 1'7. Upon deflection oi the key handle 18 to the left, non-resilient arm 17 by impinging upon blade 11 causes the latter to break contact at 12 thereby opening the circuit traced through resistances R1 and R2. Similarly deflection oi the key handle to the right causes arm 16 to move blade 9 out of contact with 8 again breaking the circuit through resistances R1 and R2.

Operation of key H to right or left thus removes the biasing potential applied to grid G and simultaneously permits the accumulated charge on condenser C to discharge through resistance R2 in shunt thereto. As the condenser discharges the grid G becomes less negative relative to the cathode as a consequence of which there results a rapid increase 01' anode current through the winding of relay D, resulting in its almost instantaneous operation to break at contact 13 the discharge circuit of condenser C through resistance R2.

Assuming key H deflected to the left, operation 01' relay D completes a circuit from point 6 of the anode circuit, through contacts 8 and 9 of switch Hf; through blade 8 and arm 16, now in contact therewith, through contacts 19, over conductor 20, resistance R3, make contacts 21 associated with the relay armature to grid G and thence through condenser C to the cathode.

Due to completion oi the circuit traced, condenser C again commences to charge up through resistance R: to the negative potential of point 15 relative to point 6 at a rate depending on the ratio of capacity C to resistance R3. As condenser C charges up, the increasingly negative potential applied to the grid reduces the flow of space current in the tube and relay winding to such a value that the relay releases to reconnect resistance R2 across condenser C. Condenser C thereupon discharges through resistance R2 at a rate depending upon the ratio of condenser C to resistance Rz, until the space current has increased sufficiently to reoperate the relay, whereupon the entire sequence of operations is repeated continuously at a certain periodicity so long as key H is deflected to the left.

Reslstances R2 and R: are so related to the capacity of C, that the intermittent operation and release of relay D occurs at such rate as to produce a succession of dots in the telegraph code.

High frequency signals corresponding to each dot are radiated from antenna A as a result of closure of switch contacts 4 and 5 under control of the relay.

Assuming key H operated to the right the same sequence of relay operations occurs automatically and continuously, but at a slower rate corresponding to dashes of the telegraph code. This results from opening of key contacts 19 which removes the short circuiting path 20 from a resistance R4 arranged in series with resistance R3. Condenser C will accordingly charge at a slower rate than heretofore as determined by the ratio of condenser C to the sum of the resistances R3 and R4 in series, which are properly proportioned to transmit dashes.

In the operation of the system resistances R2, R3 and R4 are adjusted for the correct relative proportioning with time of the short spaces. dots and dashes. Once these resistances are thus relatively adjusted, the speed of sending maybe increased or decreased as desired, without upsetting the relations of the time intervals, by merely adjusting condenser C.

Resistance R1 is finally adjusted as close as stability will allow to the point where the relay depresses. This is to minimize delay in initial operation of the relay when key H is deflected from neutral. Key H can be adjusted to have only a few mils clearance at the contacts, as the current is negligible.

For transmission of a long space, key 7 is provided, operation of which opens the circuit to all of the resistance elements R thereby permitting relay D to operate and remain operated so long as the key contacts are open.

Application of spurious potentials to the grid G, such as would result from appreciable fluctuations in the potential of point 6 relative to cathode K, has a deleterious effect on circuit operation. To minimize such fluctuations the glow discharge tube N, having a resistance large in comparison with the impedance 0! the relay, is inserted in series therewith. A tube of this character is ideally adapted to minimize potential variations of point 6 due to the fact that within the region of glow discharge the potential drop varies but slightly for relatively wide fluctuations in current through the relay winding. Tube N may be replaced by a simple resistance, but then the operation is not so effective.

I claim:

1. Signaling apparatus comprising a thermionic tube, a relay traversed by space current thereof, a condenser controlling by its charge the grid potential of said tube, means including contacts of said relay for producing its intermittent operation at a selected periodicity by alternate charge and discharge of said condenser through resistance, and a telegraph key controlling said intermittent operation.

2. Signaling apparatus comprising a thermionic tube, a relay traversed by space current thereof, a condenser controlling by its charge the grid potential of said tube, means including contacts of said relay for producing intermittent operation thereof by alternate charge and discharge of said condenser through resistance, said means including a telegraph key having a neutral position preventing said relay operation, a first operating position for producing relay operation at one periodicity, and a second operating position producing relay operation at a second periodicity.

3. Telegraph transmitting apparatus comprising a thermionic tube, a relay traversed by space current thereof, a condenser controlling by its charge the grid potential of said tube, means including contacts of said relay for producing its intermittent operation by alternate charge and discharge of said condenser through resistance, said means including a telegraph key having a neutral and two operating positions adapted respectively, to stall said relay, to cause its intermittent operation at a periodicity corresponding to telegraph dots, and its intermittent operation at a periodicity corresponding to telegraph dashes.

4. Telegraph transmitting apparatus comprising a thermionic tube, a relay traversed by space current thereof, a condenser controlling by its charge the grid potential of said tube, means including contacts of said relay for producing its intermittent operation by alternate charge and discharge of said condenser through resistance, said means including a telegraph key having a neutral and two operating positions adapted respectively, to stall said relay, to cause its intermittent operation at a periodicity corresponding to telegraph dots, and its intermittent operation at a periodicity corresponding to telegraph dashes, said resistance and capacity being adjustable for varying said periodicities, and telegraph transmitting means controlled by said relay.

5. Signaling apparatus comprising a thermionic tube, a relay traversed by the space current thereof, a condenser controlling by its charge the grid potential of said tube, and means responsive to said relay for discharging'said condenser through a resistance to operate said relay and for thereafter charging said condenser through a second resistance to release said relay whereby intermittent operation ensues, and a switch for controlling said operation.

6.'Telegraph transmitting apparatus comprising a thermionic tube having an anode, a cathode and a grid, a condenser between grid and cathode, a relay in a connection between anode and cathode, a glow discharge tube in series with said relay adapted to maintain the potential drop from a point of said connection to said cathode, substantially constant in the presence of current variations through said relay, means responsive to said relay including a parallel path from said point to the cathode for providing intermittent relay operation by alternate charge and discharge of said condenser through resistance, and a telegraph key in said path for controlling said intermittent operation.

7, Telegraph transmitting apparatus comprising a thermionic tube, a relay traversed by space ,zrrent thereof, a condenser controlling by its charge the grid potential of said tube, a telegraph key having a neutral and two operating positions, means responsive to said neutral position for applying a charge of said condenser preventing relay operation, means responsive to each operating position of said key for intermittently operating said relay by alternate charge and discharge of said condenser through resistance at periodicities corresponding to dots and dashes for the respective key operating positions.

8. Signaling apparatus comprising a thermionic tube, a relay traversed by space current thereof, a condenser controlling by its charge the grid potential of said tube, means including contacts of said relay for producing its intermittent operation at a selected periodicity by alternate charge and discharge of said condenser, and a telegraph key controlling said intermittent operation.

ROSWELL WARD GILBERT. 

